Closure cap with audible warning

ABSTRACT

A closure cap ( 10 ) is provided with an audible warning when the cap ( 10 ) is removed from a container ( 12 ). The closure cap ( 10 ) preventing the inadvertent consumption of pharmaceutical products, bleaches or other products by children or other minors. In use, the closure cap ( 10 ) may be provided with child resilient means and can be screwed on to any standard container ( 12 ). When the cap ( 10 ) is removed from the container ( 12 ), mechanical energy is expended by the user and such mechanical energy is converted to sufficient electrical energy using a piezoelectrical element ( 14 ) contained in the cap ( 10 ). The electrical energy generated is then conditioned and stored using signal conditioning electronics ( 26 ) such that and alarm signal of sufficient level is sounded. In use, the piezoelectrical element ( 14 ) is interposed between two sprung steel sections ( 16 ) formed as a dome and the action of unscrewing the cap ( 10 ) causes the sprung sections ( 16 ) to snap back producing a large dynamic force on said piezoelectrical element ( 14 ) which produces a large voltage output.

The present invention relates to a closure cap with audible warning. Inparticular, the present invention relates to an apparatus for providingan audible warning when the cap is removed from a container.

The most important aspect when storing any consumable products is thatan airtight seal must be made and maintained between the closure cap andthe container. A simple technique for indicating the integrity of a sealinvolves the use of a ‘safety button’, whereby the container, which isfirstly filled with the consumable product, is held at a slightlyreduced pressure prior to adding the closure cap. For as long as theseal remains intact, the reduced pressure in the container is sufficientto retain an indent inside the cap. When the cap is removed, thepressure in the container equalises and the indent becomes raised.Whilst these simple devices have proven popular for certain products,they suffer the main disadvantage that they only operate when the cap isinitially removed from the container. There is therefore the need forclosure cap which provides an alarm condition every time the cap isremoved from the container. Such a device could be utilised as ananti-tamper indicator or as part of a child resistant packaging forprotecting the inadvertent consumption of pharmaceutical products,bleaches or other products by children or other minors.

In recent years, child resistant containers have become commonplace.Generally, such containers have a closure cap which can only be removedby depressing the mechanism against a resilient locking mechanism. Thebenefits of these containers are well known, and it is believed thatsince child resistant packaging of prescription medicines was introducedin the United States in the 1970's, the fatality rate was reduced by upto 45%. However, the accident figures have recently been climbing, dueto a large measure to the improved motor skills of young children withsophisticated modern toys.

Analysis of the statistics for child poisoning show that approximately50% of accidents are due to first or second generation parents leavingprescription medicines or hazardous domestic chemicals, such as bleach,with the caps loose, or off, or in containers without child resistantcaps. In the other 50% of accidents, the children simply overcame themechanism of the child resistant cap. Although many different techniqueshave been proposed to improve child resistant packaging in recent years,none have been entirely successful and it is difficult to envisage amechanical solution to this problem, largely due to the fact that thecap, which must defeat a child gaining access, must also be accessibleto an elderly person with probably somewhat reduced motor skills.

It is the object of the present invention to provide a closure cap withaudible warning. The present invention provides an audible alarm whenthe seal between a closure cap and a container is broken, and hence maybe used as an indicator of the integrity of said seal. The presentinvention preventing the inadvertent consumption of pharmaceuticalproducts, bleaches or other products by children or other minors, aswhen the cap is removed from the container an audible warning is soundedso that a responsible adult is alerted to replace the cap in areasonable time and before an accident occurs. The present inventionenabling the secure storage of pharmaceutical products, bleach or otherproducts in a simple and economic package, the physical dimensions ofwhich must be compatible with caps on conventional containers to allowretrofitting if required. It is a further object of the presentinvention to provide a cap with anti-tamper warning that is self-poweredand having low-power electronics to drive an audible warning device whenthe cap is removed from the container.

According to the present invention there is provided a cap adapted toengage with a container, comprising:

an electrical generation means for converting the mechanical energyexpended on removing said cap from said container into electricalenergy;

signal conditioning circuitry for conditioning and storing saidelectrical energy; and

a warning means for generating an alarm condition.

In use, said cap is adapted to engage with said container via a screwthread. Preferably, said cap being formed from polypropylene or moldedfrom a suitable plastics material. Further, in use, said cap havingphysical dimensions compatible with standard containers ofpharmaceutical products, bleach or other products. Said cap may alsoinclude child resistant measures, such as, for example, a resilientlocking mechanism.

In a preferred embodiment, said electrical generation means furthercomprises a piezoelectric element. Said piezoelectric element beingformed from a suitable piezoceramic material or polyvinylidene fluoridefilm. In one embodiment, said piezoelectric element is interposedbetween said cap and said container, such that a compressive force actsto compress the full area of said piezoelectric element. Upon removal ofsaid cap, the compressive force on said piezoelectric element is removedand an output voltage is produced which is proportional to the intrinsicproperties and physical dimensions of the piezoelectric element.

In order to increase the output voltage produced by said piezoelectricelement, the electrical generation means may further comprise a triggermechanism for producing a dynamic force on said piezoelectric elementwhen the user removes said cap from said container. In use, thepiezoelectric element is preferably located between two sprung steelsections and the action of unscrewing the cap causes the sprung steelsections to ‘snap’ back, producing a large dynamic force on saidpiezoelectric element. Preferably, said piezoelectric element wouldinitially produce a voltage output due to a compressive force across itsthickness direction closely followed by a much larger but additionalvoltage due to stretch along its length axis as the sprung steelsections ‘snap’ back. The ‘snap’ force of the sprung steel sections willbe a function of the type of mechanism incorporated in said cap.

In an alternative embodiment, said electrical generation means furthercomprises an electromechanical generator. In use, a mechanism isprovided which gives sufficient motion of a coil linking a fixedmagnetic field to produce said electrical energy.

Further preferably, the output voltage generated by said electricalgeneration means is fed to signal conditioning circuitry which performthe steps of voltage reduction, charge storage, voltage regulation anddrive oscillation prior to activating said warning means.

In a preferred embodiment, said warning means further comprises anaudible sounder, being located in said cap. For normal adult use, saidaudible sounder acts as a reminder to replace the cap when the containerhas been used. When said cap is removed by a child, the audible sounderis sufficiently loud to preferably warn an adult on the premises thatthe container has been opened. Preferably, a sound pressure level of atleast 75 dBA is produced. In one embodiment, said audible sounder, whichneed only ‘bleep’ intermittently, should continue until said cap isreplaced. However, with limited energy available from a single capremoval, the audible sounder will preferably sound for a finite time,which should be for at least 10 seconds after the cap is removed toallow the user time to access the contents of the container, butsufficient to provide warning of child access. In use, said audiblesounder may be provided by an electromagnetic or piezoelectric sounder,although to reduce energy requirements the latter is preferred.

In an alternative embodiment, said warning means may be implemented as aremote system, whereby on removal of said cap from said container analarm condition is transmitted to a remote receiver and audible sounder.In use, this may be achieved using a uniquely identified radio frequencytag embedded in said cap.

Also according to the present invention there is provided a cap adaptedto engage with a container for detecting the relative position betweensaid cap and said container, comprising:

a piezoelectric element for generating an electrical output when saidcap is removed from said container; and

an audible sounder, being driven by said electrical output of saidpiezoelectric element.

The advantages of the present invention are that a closure cap withaudible warning is provided. The present invention provides an audiblealarm when the seal between a closure cap and a container is broken, andhence may be used as an indicator of the integrity of said seal. Thepresent invention preventing the inadvertent consumption ofpharmaceutical products, bleaches or other products by children or otherminors, as when the cap is removed from the container an audible warningis sounded so that a responsible adult is alerted to replace the cap ina reasonable time and before an accident occurs. The present inventionenabling the secure storage of pharmaceutical products, bleach or otherproducts in a simple and economic package, the physical dimensions ofwhich must be compatible with caps on conventional containers to allowretrofitting if required. In use, the cap with anti-tamper warning isself-powered and has low-power electronics to drive an audible warningdevice when the cap is removed from the container.

It will be obvious to those skilled in the art that variations of thepresent invention are possible and it is intended that the presentinvention may be used other than as specifically described herein.

A specific non-limiting embodiment of the invention will be described byway of example and with reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram of the present invention.

FIG. 2 illustrates how a voltage may be obtained from a piezoelectricelement.

FIG. 3 shows how the cap with anti-tamper warning according to thepresent invention may be implemented.

FIG. 4 schematically illustrates further detail of the signalconditioning electronics.

FIG. 5 shows how the voltage obtained from the piezoelectric element isfirstly rectified to a suitable DC level.

FIG. 6 shows further detail of the charge storage circuit shown in FIG.4.

FIG. 7 illustrates a suitable drive oscillator for driving apiezoelectric sounder.

FIG. 8 shows how the present invention may be implemented using a remotealarm sounder.

Referring now to the drawings, wherein the present invention isillustrated schematically in FIG. 1. In use, a cap with anti-tamperwarning according to the present invention is screwed on to any standardcontainer capable of storing pharmaceutical products, bleaches or anyother products that could be poisonous or otherwise dangerous ifinadvertently consumed by children or other minors. When the cap isremoved from the container, mechanical energy is expended by the userand, according to the present invention, such mechanical energy isconverted to sufficient electrical energy using a piezoelectric elementcontained in the cap. The electrical energy generated is thenconditioned and stored using signal conditioning electronics such thatan alarm signal of sufficient level is sounded. In this way, if the caphas been removed by a child or other minor, a responsible adult would bealerted, and could replace the cap in a reasonable time and before anaccident occurs.

FIG. 2 shows schematically how a piezoelectric element can be used toconvert mechanical energy into electrical energy. Piezoelectricity isthe general term used to describe the property exhibited by certainmaterials of becoming electrically polarised when stress is applied tothem. In a preferred embodiment of the present invention, thepiezoelectric element may be implemented using a group of piezoceramicsknown as PZTs, or alternately an organic PVDF (polyvinylidene fluoride)film or various copolymers.

FIG. 2 shows a piezoelectric element in the form of a plate havinglength L, Width W and thickness t. The most widely used piezoelectriccoefficients, d_(em) and g_(em), for charge and voltage respectively,use subscripts to indicate the electrical (e) and mechanical (m) axesused. Since electrical contacts are normally made the top and bottom ofthe plate, e is usually axis 3. The mechanical axis is m=1 for stress onthe. length axis, or m=3 for stress supplied through the thickness ofthe element.

By way of example, if a 2 psi (5.6 N) load is applied to thepiezoelectric element shown in FIG. 2 having a length and width of 2 cmand a thickness of 1 mm. The force acts to compress the element'sthickness (g₃₃ mode) across its full area, and the open circuit outputvoltage V_(OC) for both PZT and PVDF elements is given by V_(OC)=g₃₃F₃t/L W. For a typical PZT element, where g₃₃=26.5×10⁻³, the opencircuit output voltage V_(OC) is only 0.37V. For a typical PVDF element,where g₃₃=339×10⁻³, the open circuit output voltage V_(OC) is 4.75V.

From the above analysis, it is clear that the open circuit outputvoltage produced from a quasi-static force (as would be expected whenunscrewing the cap) is probably insufficient to drive an alarm sounder.However, piezoelectric elements are excellent for handling dynamic andtransient forces, so to raise the converted electrical energy to asufficient level it is necessary to include a trigger mechanism into thecap which produces a reasonable dynamic force acting on the piezoeletricelement when the cap is removed.

FIG. 3 illustrates how this may be implemented in the present invention,and shows a cap 10 according to the present invention which is locatedon suitable container 12. The contents of the container 12 are sealedfrom the anti-tamper warning mechanism using wad 22. A piezoelectricelement 14 is interposed between two sprung steel sections 16 formed asa dome. As previously mentioned, the piezoelectric element 14 respondsbest to dynamic input forces rather than static or quasi-static forces,and the piezoelectric element 14 receives a sudden stress when the capis slowly removed. The piezoelectric element 14 attached to the snapdome 16 would, when activated, produce a high output voltage in excessof 300V.

When in a closed position, a projection or bump 18 deforms the sprungsteel sections 16 via spring 20. Since the piezoelectric element 14 isattached to both sprung steel sections 16, the action of unscrewing thecap 10 allows the snap dome 16 to ‘snap’ back and the piezoelectricelement 14 will be stretched along the length axis (g₃₁ mode), theforces remaining constant until the cap 10 is restored on the container12. The force applied and the snap force of the spring will be afunction of the type of mechanism incorporated in the cap 12. In use, itis envisaged that the piezoelectric element 14 would initially produce avoltage output due to compression force in the ‘33’ direction closelyfollowed by a much larger but additional voltage due to stretch in the‘31’ direction as the sprung steel sections 16 ‘snaps’ back. In analternative embodiment, it is envisaged that the present invention couldbe implemented with a single spring section 16.

The output of the piezoelectric element 14 is then fed to the signalconditioning electronics 26 located on a surface mount PCB 24 andultimately to the alarm sounder 28. Further details of this are shownschematically in FIG. 4, with each element of FIG. 4 being dealt with indetail in FIGS. 5, 6 and 7.

Since the voltage generated by the piezoelectric element may be severalhundred volts in magnitude, it is necessary to reduce this energy to asuitable value prior to storing such and activating the alarm sounder.FIG. 4 shows the reduction of the potential energy (voltage) of thepiezocharges from many hundreds of volts to only a few volts suitablefor powering the microcircuitry of CMOS integrated circuits. It requiresthree circuit functions as shown, and comprises a voltage reduction andcharge storage stage; voltage regulation stage; and drive oscillatorcircuit for the alarm.

The output from the piezoelectric element is bipolar in nature since theelement is first compressed and then stretched, as described previously.As such, a bridge rectifier as shown in FIG. 5 will be required. It isimportant to note that, with larger voltage levels, the peak inversevoltage of the diodes in the bridge must not be exceeded.

The output of the bridge rectifier is then fed to the charge controlcircuit depicted in FIG. 6, which senses the voltage built up oncapacitor C₁, and includes a basic Zener diode regulator. Assuming thata 300 nF piezoelectric element capacitance is achievable (depending onthe permittivity and physical dimensions of the element), then thevoltage developed across the 1 μF capacitor C₁ could reach 300V from a1kV piezoelectric output. The Zener voltage would be chosen within themaximum voltage input for the regulator. Providing the capacitor C₁charges sufficiently quickly (low internal film resistance), this wouldprovide enough current through the regulator to power the CMOSoscillator and alarm sounder for several seconds.

A alternative solution would be to use a switching converter, based oncurrently available commercial chips, which is a true power converter,and is capable of providing an average DC output current larger than theaverage DC input current.

In use, the audible sounder used may be provided by an electromagneticor piezoelectric sounder, although to reduce energy requirements thelatter is preferred. FIG. 7 shows a suitable drive oscillator fordriving a piezoelectric sounder. The values of C, R₁ and R₂ are chosento give a frequency of 1 pulse per second (pps). FIG. 7 shows a driverespecially suited for driving a piezoelectric sounder that are usedwidely in battery driven equipment such as smoke alarms etc.Piezoelectric sounders use the opposite energy transfer to thatdescribed for the piezoelectric element. An electrical signal appliedacross the face of a piezoceramic bender plate element will causemechanical distortion due to the piezoelectric effect.

When an alternating voltage is applied across the electrodes, thediaphragm alternates bending in the two directions, producing soundwaves in air. Typically, the piezoelectric diaphragm does not by itselfproduce a high sound pressure level (SPL). It is necessary to mount thebender diaphragm in a resonant cavity to enhance the SPL at a specificfrequency. Thus in choosing a sounder it is necessary to know itsresonant frequency and then design the frequency of the drivingoscillator to be as close to that value as possible in order to maximiseSPL, and hence volume.

Manufacturers can supply the sounders with the required drive circuitbuilt into the package (self drive) or requiring the user to provide thedrive oscillator externally to the package (external drive). The formeris preferred, as the internal drive oscillator has a feedback connectionfrom the disc, which allows it to be tuned more closely to the naturalfrequency of the sounder, giving optimum SPL.

Using external drive circuits, such as the single chip inverteroscillator shown in FIG. 7, the component values must be reasonablystable, and the power supply to the CMOS inverters must also be wellregulated, in order to maintain the natural resonant frequency of thecavity and give the best output SPL. In FIG. 7, inverters 1 and 2 forman astable oscillator while Inverter 3 acts as a buffer to shape thewaveform. The equation for the frequency of oscillation f_(ocs) is givenby f_(ocs)=1/2.2 R₁ C, where R₂≅10 R₁.

FIG. 8 shows an alterative embodiment of the present invention, wherebythe alarm sounder located inside the cap is replaced by a remote alarmsystem, since the major problems in designing a self-powered alarm forthe cap is that the alarm circuit requires reasonable energy to driveit. An alternative system would be to mount the alarm remotely and causethe cap to signal its state to the alarm circuit.

FIG. 8 shows that a radio frequency identification tag (RFID) couldimplemented inside the cap, and which could transmit an alarm condition(via an identification code) to a central receiver. In use, passive tagsmay be used, which are powered continuously from the receiver, whichtransmits a strong RF signal. This signal is received by the tagantenna, powering the microcircuits which contain the identificationcode and causing a backscatter signal modulated by the code data. Thisdata is received, decoded and stored by the receiver unit.

These tags are very small and could easily be inserted under the wadsealer in the cap. Additionally, it is also envisaged that the containeritself could be tagged so that the removal of the container to anywhereoutside the transmit/receive distance would activate the alarm.

Various alterations and modifications may be made to the presentinvention without departing from the scope of the invention. Forexample, although particular embodiments refer to providing an audiblewarning so that the inadvertent consumption of pharmaceutical products,bleaches or other products by children or other minors is prevented,this is in no way intended to be limiting as, in use, the presentinvention may be implemented so that the audible sounder acts simply asa reminder to replace the cap when the container has been used. Thepresent invention, which provides an audible alarm when the seal betweena closure cap and a container is broken, may be used with any consumableproducts to warn any person that the integrity of the seal isquestionable.

1. A cap adapted to engage with a container, comprising: an electricalgeneration means for converting mechanical energy expended on removingsaid cap from the container into electrical energy; signal conditioningcircuitry for conditioning and storing the electrical energy; and awarning means for generating an alarm condition.
 2. A cap as claimed inclaim 1, wherein said electrical generation means comprises apiezoelectric element.
 3. A cap as claimed in claim 1, wherein saidsignal conditioning circuitry comprises a voltage reduction and chargestorage stage, a voltage regulation stage and a drive oscillation stage.4. A cap as claimed in claim 3, wherein said voltage reduction andcharge storage stage comprises a bridge rectifier.
 5. A cap as claimedin claim 3, wherein said voltage regulation stage comprises a capacitorand Zener diode regulator.
 6. A cap as claimed in claim 3, wherein saiddrive oscillation stage comprises a single chip inverter oscillatorwhich is tuned to a natural frequency of said warning means.
 7. A cap asclaimed in claim 1, wherein said warning means comprises an audiblesounder.
 8. A cap as claimed in claim 1, wherein said warning meanscomprises a remote alarm system, whereby on removal of said cap from thecontainer the alarm condition is transmitted to a central receiver andan audible sounder.
 9. A cap as claimed in claim 8, wherein said remotealarm system comprises a uniquely identified radio frequency tagembedded in said cap which transmits the alarm condition via anidentification code to said central receiver.
 10. A cap as claimed inclaim 9, wherein said uniquely identified radio frequency tag is apassive tag which is powered continuously by said central receiver. 11.(canceled)
 12. A cap as claimed in claim 1, wherein said electricalgeneration means comprises an electromechanical generator.
 13. A cap asclaimed in claim 12, wherein said electromechanical generator comprisesa coil linking a fixed magnetic field to produce the electrical energy.14. A cap adapted to engage with a container for detecting tea relativeposition between said cap and the container, comprising: a piezoelectricelement for generating an electrical output when said cap is removedfrom the container; and an audible sounder, being driven by theelectrical output of said piezoelectric element.
 15. A cap as claimed inclaim 1, wherein said cap is adapted to engage with said container via ascrew thread.
 16. A cap as claimed in claim 1, wherein said cap isformed from polypropylene or molded from a suitable plastics material.17. A cap as claimed in claim 1 wherein said cap has physical dimensionscompatible with standard containers of pharmaceutical products, bleachor other products.
 18. A cap as claimed in claim 1, further comprisingchild resistant measures, such as, a resilient locking mechanism.
 19. Acap as claimed in claims 2, wherein said piezoelectric element is formedfrom a suitable piezoceramic material or polyvinylidene fluoride film.20. A cap as claimed in claim 19, wherein said piezoelectric element isinterposed between said cap and the container, such that a compressiveforce compresses a full area of said piezoelectric element.
 21. A cap asclaimed in claim 20, wherein, upon removal of said cap, the compressiveforce on said piezoelectric element is removed and an output voltage isproduced which is proportional to intrinsic properties and physicaldimensions of said piezoelectric element.
 22. A cap as claimed in claims2, wherein said electrical generation means further comprises a triggermechanism for producing a dynamic force on said piezoelectric elementupon removal of said cap.
 23. A cap as claimed in claim 22, wherein saidtrigger mechanism comprises two spring steel sections formedsubstantially as a dome.
 24. A cap as claimed in claim 23, wherein saidpiezoelectric element is located between said two spring steel sectionsand unscrewing said cap causes said spring steel sections to ‘snap’back, producing a large dynamic force on said piezoelectric element. 25.A cap as claimed in claim 24, wherein said piezoelectric elementinitially produces a large voltage output due to a compressive forceacross a thickness direction thereof closely followed by a much larger,but additional voltage due to stretch along a lengthwise axis thereof assaid spring steel sections ‘snap’ back.
 26. A cap as claimed in claims7, wherein said audible sounder produces a sound pressure level to alerta user that said cap has been removed.
 27. A cap as claimed in claim 26,wherein the sound pressure level of at least 75 dBA is produced uponremoval of said cap.
 28. A cap as claimed in claim 26, wherein saidaudible sounder bleeps intermittently and continues until said cap isreplaced.
 29. A cap as claimed in claim 26, wherein said audible soundercomprises an electromagnetic or piezoelectric sounder.
 30. A cap asclaimed in claim 26, wherein said audible sounder indicates an integrityof a seal between said cap and.
 31. (canceled)
 32. (canceled)
 33. Capand container system comprising: a cap as claimed in claim 8; and acontainer that is tagged so that removal of the container to anywhereoutside of a footprint of said central receiver activates an alarmcondition.
 34. A cap as claimed in claim 14, wherein said cap is adaptedto engage with said container via a screw thread.
 35. A cap as claimedin claim 14, wherein said cap is formed from polypropylene or moldedfrom a suitable plastics material.
 36. A cap as claimed in claim 14,wherein said cap has physical dimensions compatible with standardcontainers of pharmaceutical products, bleach or other products.
 37. Acap as claimed in claim 14, further comprising child resistant measures,such as a resilient locking mechanism.
 38. A cap as claimed in claim 14,wherein said piezoelectric element is formed from a suitablepiezoceramic material or polyvinylidene fluoride film.
 39. A cap asclaimed in claim 38, wherein said piezoelectric element is interposedbetween said cap and the container, such that a compressive forcecompresses a full area of said piezoelectric element.
 40. A cap asclaimed in claim 39, wherein, upon removal of said cap, the compressiveforce on said piezoelectric element is removed and an output voltage isproduced which is proportional to intrinsic properties and physicaldimensions of said piezoelectric element.
 41. A cap as claimed in claim14, wherein said electrical generation means comprises a triggermechanism for producing a dynamic force on said piezoelectric elementupon removal of said cap.
 42. A cap as claimed in claim 41, wherein saidtrigger mechanism comprises two spring steel sections formedsubstantially as a dome.
 43. A cap as claimed in claim 42, wherein saidpiezoelectric element is located between said two spring steel sectionsand unscrewing said cap causes said spring steel sections to ‘snap’back, producing a large dynamic force on said piezoelectric element. 44.A cap as claimed in claim 43, wherein said piezoelectric elementinitially produces a large voltage output due to a compressive forceacross a thickness direction thereof closely followed by a much larger,but additional voltage due to stretch along a lengthwise axis thereof assaid spring steel sections ‘snap’ back.
 45. A cap as claimed in claim14, wherein said audible sounder produces a sound pressure level toalert a user that said cap has been removed.
 46. A cap as claimed inclaim 45, wherein the sound pressure level of at least 75 dBA isproduced upon removal of said cap.
 47. A cap as claimed in claim 45,wherein said audible sounder bleeps intermittently and continues untilsaid cap is replaced.
 48. A cap as claimed in claim 45, wherein saidaudible sounder comprises an electromagnetic or piezoelectric sounder.49. A cap as claimed in claim 45, wherein said audible sounder indicatesan integrity of a seal between said cap and the container.